Cassette loading/unloading apparatus for cassette tape recorder

ABSTRACT

In a cassette loading/unloading apparatus for a slot-in type cassette tape recorder using a toggle spring, a slider holds a cassette inserted therein and slides together therewith in a cassette holder. The cassette loading/unloading apparatus is provided with a spring member separate from the toggle spring. This spring member is charged with a biasing force as the slider slides at cassette insertion so that the charged biasing force may act as a resisting force on the slider. The spring member applies the resisting force to the slider before the slider passes the neutral point of the toggle spring, and is prevented from doing so after the slider passes the neutral point.

BACKGROUND OF THE INVENTION

This invention relates to a cassette loading/unloading apparatus forcassette tape recorder.

In a slot-in type cassette tape recorder utilizing a toggle spring, acassette is pushed into a cassette holder against the biasing force ofthe toggle spring at cassette insertion until it reaches the neutralpoint of the toggle spring. When the neutral point of the toggle springis passed, the biasing force of the toggle spring acts so as to draw thecassette in the cassette holder, and thus the cassette is instant drawninto the cassette holder. The stroke of the cassette terminating at theneutral point of the toggle spring is called pushing-in stroke, whilethe stroke starting at the neutral point is called drawing-in stroke.The length of each stroke is proportional to the biasing force producedin the toggle spring. If the drawing-in stroke is large, the biasingforce of the toggle spring to act after the cassette is drawn in thecassette holder may be set at a high level, so that the cassette can beloaded securely. If the psuhing-in stroke is large, on the other hand,the biasing force of the toggle spring to act as an ejecting force atcassette ejection may be set at a high level, so that the cassetteejection can be ensured.

Since the biasing force of the toggle spring acts as a resisting forceagainst cassette insertion in the drawing-in stroke, it is not advisableto make the drawing-in stroke very large. If the drawing-in stroke istoo small, on the other hand, it will be started before the cassettewill be held satisfactorily in the cassette holder, failing to ensuresteady cassette loading. Namely, for secure cassette loading, it isnecessary that a proper resisting force be applied to the cassette inthe pushing-in stroke.

In general, the toggle spring is so disposed that the pushing-in anddrawing-in strokes are equal in length. There are known two types ofcassettes; compact cassette and micro cassette whose surface area isapproximately 1/4 of that of the compact cassette. With the compactcassette, which is relatively large-sized, both strokes can generally belarge enough to ensure both cassette insertion and ejection. With themicro cassette, however, neither of the strokes can be large due to thelimited cassette size. In some cases, it is difficult to make thestrokes large enough even with the compact cassette because of thepositional relations with other members and limited space.

Staar and counter-Staar type cassette tape recorders are known asslot-in type cassette tape recorders.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a cassetteloading/unloading apparatus for cassette tape recorder capable of securecassette insertion and ejection even with use of limited pushing-instroke.

To this end, according to the invention, a spring member to be chargedwith a biasing force as the slider slides at cassette insertion isprovided separately from the toggle spring. The charged biasing forcemay act as a resisting force on the slider.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the sameis read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for purpose ofillustration only and is not intended as a definition of the limits ofthe invention.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 and 10 to 12 are schematic right side views of a cassette taperecorder provided with a cassette loading/unloading apparatus accordingto this invention, partially represented by one-dot chain lines forsimplicity of drawing, in which:

FIG. 1 shows a state before the insertion of a cassette;

FIG. 10 shows a state after the cassette insertion and before thedescent of a cassette holder;

FIG. 11 shows a state after the descent of the cassette holder; and

FIG. 12 shows a state after the ascent of the cassette and before thecassette ejection.

FIGS. 2 to 9 are right side views of principal parts of the cassettetape recorder, in which:

FIG. 2 shows the cassette holder;

FIG. 3 shows a slider;

FIG. 4 shows a baseplate;

FIG. 5 shows a rocking plate;

FIG. 6 shows an operating plate;

FIG. 7 shows a stopper plate;

FIG. 8 shows an ejecting plate; and

FIG. 9 shows a kick plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, a cassette tape recorder 10 is provided with aslot-in type cassette loading/unloading apparatus 12 utilizing a togglespring. A baseplate 14 is fixed on a chassis (not shown), and a cassetteejecting mechanism 16 is disposed on the baseplate 14. Capable of movingup and down, the cassette loading/unloading apparatus 12 is normallylocated in an upper position, and is moved to a lower position toestablish an operation mode such as a reproduction mode when a cassetteis inserted thereinto. When an ejecting plate 18 of the ejectingmechanism 16 is pressed, the cassette loading/unloading apparatus 12 ismoved from the lower position to the upper position, and the cassette isthen ejected.

As seen from FIG. 1, the cassette loading/unloading apparatus 12includes a cassette holder 20 capable of ascent and descent and in whichthe cassette is inserted and set, and a slider 22 which slides in thecassette holder 20, holding the cassette inserted in the cassette holder20. As shown in FIG. 2, the cassette holder 20 includes a pair of sideplates (only right side plate 24 shown in FIG. 2) and a top plate 26connecting the side plates, and a guide strip 28 extends horizontallyinward from the lower edge of each side plate. A pair of horizontalguide slots 30 and 31 are formed in the right side plate 24 to serve asguide grooves for the slider 22. Further, a pair of pins 32 and 33 areerected on the right side plate 24 to extend outward therefrom. Theslider 22 is so disposed as to hold the right side plate 24. As seenfrom FIG. 3, moreover, the slider 22 includes a U-shaped supportingstrip 38 located inside the right side plate 24 to hold a cassette 36inserted in the cassette holder 20. The supporting strip 38 is formed ofan elastic plate. The slider 22 further includes a movable block 40outside the right side plate 24, and the supporting strip 38 is fixed tothe movable block 40 by a screw 41. A pair of pins 42 and 43 are erectedon the movable block 40 to extend inward thereform, and the slider 22 isallowed to slide relatively to the cassette holder 20 with the pins 42and 43 fitted in the slots 30 and 31, respectively, of the cassetteholder 20 (see FIG. 1). Attached to the outer face of the movable block40 are a flat, wedge-shaped cam strip 46 and a plastic guide strip 50with a vertically elongated guide slot 48 formed therein.

As shown in FIG. 4, the baseplate 14 fixed on the chassis includes ahorizontal plate 52 located on the chassis, a bent plate 53 extendingupward from the right side edge of the horizontal plate 52, and a pairof bent plates 54 and 55 extending upward from the left side edge of thehorizontal plate 52. A pair of pins 58 and 59 are erected on the bentplate 54 to extend outward therefrom. The pin 58 serves as the rockingcenter of a rocking plate 60 mentioned later, while the pin 59 functionsas a supporting pin for a tension coil spring 62 mentioned later (seeFIG. 1). A release plate 64 is screwed to the bent plate 55. Formed ofan elastic member such as a spring, the release plate 64 is bent twiceat right angles at a shoulder portion 66 in the middle so as to have itsfree end portion located inside its basal portion. The release plate 64is so designed as to be pressed by the cam strip 46 to be curved outwardas the slider 22 slides. Five pins 68, 69, 70, 71 and 72 are erected onthe bent plate 53, the pins 68 and 69 extending inward and the pins 70,71 and 72 outward. The outwardly extending pins 70 and 71 are fitted intheir corresponding horizontal slots 74 and 75 of the ejecting plate 18to guide the ejecting plate 18 in slide (see FIG. 1). On the other hand,a kick plate 76 (see FIG. 1) of the ejecting mechanism 16 is rockablymounted on the bent plate 53 by the inwardly extending pin 68, and atorsion coil spring 78 is wound around the other inwardly extending pin69. A holder supporting plate 80 (see FIG. 1) is rockably mounted in theform of an overbridge by the pin 72 and its counterpart (not shown) onthe left side, supporting the cassette holder 20 in the upper position.Stopper strips 82 and 83 protrude outward from the upper edge of thebent plate 53. The stopper strip 82 serves as a stopper for a tensioncoil spring 84 as a return spring for the ejecting plate 18, while thestopper strip 83 functions as a stopper for regulating the rockingposition of the holder supporting plate 80.

As shown in FIGS. 1 and 5, the rocking plate 60 rockably mounted on thebaseplate 14 by the pin 58 has an inwardly extending pin 86 erected onits upper end portion, and a plastic ring 88 is fitted on the pin 86.The ring 88 is of such a size that it can move up and down inside theguide slot 48 of the movable block 40. Adjoining the pin 86, moreover, apin 90 is erected on and protrudes from the rocking plate 60, and thetension coil spring 62 is disposed between the pin 90 and the pin 59 onthe base plate 14. The tension coil spring 62 functions as a togglespring.

When the cassette 36 is inserted into the cassette holder 20, it is heldby the supporting strip 38 of the slider 22 and slides together with theslider 22 inside the cassette holder 20, moving inward or to the rightof FIG. 1 as the cassette 36 is inserted. The rocking plate 60, which iscoupled with the movable block 40 of the slider 22 by the pin 86 and thering 88, rocks in the clockwise direction around the pin 58 as therocking center, accompanying the slide of the slider 22. In FIG. 5, aone-dot chain line represents the position of the rocking plate 60 at apoint of time when the slider 22 has reached its innermost position tocomplete the cassette insertion. As seen from FIG. 5, the pin 58 as therocking center lies on the perpendicular bisector 94 of a segment 92connecting the positions of the pin 86 before and after its rocking. Thesupporting pins 59 and 90 for the toggle spring or tension spring 62,however, are not located on the perpendicular bisector 94. Namely, thepins 59 and 90 are located on the right and left sides, respectively, ofthe perpendicular bisector 94. Further, the neutral point 98 of thetoggle spring 62, i.e., the intersection of the segment 92 and theextension of a segment 96 connecting the pins 58 and 59, is located onthe left side of the perpendicular bisector 94. In FIG. 5, Li and Ldindicate the pushing-in and drawing-in strokes, respectively, thedrawing-in stroke Ld being larger than the pushing-in stroke Li. Thebiasing force of the toggle spring 62 in the drawing-in stroke Ld can bemade substantial large enough by thus deliberately setting the fittingposition of the toggle spring 62 to make the drawing-in stroke Ld largeenough. Thus, the cassette loading can be secured, and the cassetteloading/unloading apparatus 12 can enjoy good resistance to vibration.

In such an arrangement, the larger the drawing-in stroke Ld, the smalleris the pushing-in stroke Li, and also, the smaller is the biasing orejecting force of the toggle spring 62 at cassette ejection. Asmentioned later, however, the biasing force of the torsion coil spring78 is added to the biasing force of the toggle spring 62 to provideenough ejecting force for reliable cassette ejection.

As seen from FIG. 1, an operating plate 104 is slidably attached to thecassette holder 20 with the pins 32 and 33 of the cassette holder 20fitted in slots 102 and 103, respectively. A stopper plate 106 isrockably mounted on the cassette holder 20 by the pin 32.

As shown in FIG. 6, the slots 102 and 103 of the operating plate 104have a slanting portion and a horizontal portion, respectively. Theseslots 102 and 103 differ in that the slot 102 has a vertical portion atthe right end. The operating plate 104 has an extended portion 108 atthe left end, the tip end of the extended portion 108 forming a slantingsurface 109. An outwardly bent stopper strip 112 is formed at the rightend of the operating plate 104, and a tension coil spring 114 as areturn spring for the operating plate 104 is disposed between thestopper strip 112 and the pin 32 (see FIG. 1). The operating plate 104is biased to the left of FIG. 1 by the biasing force of the tensionspring 114, so that the pins 32 and 33 are pressed by the right ends ofthe slots 102 and 103, respectively.

As shown in FIG. 7, the stopper plate 106 has a pin 116 extendingoutward from the right end portion and a stopper strip 118 bent inwardfrom the left end of the plate 106. As shown in FIG. 1, the stopperplate 106 is urged to rock clockwise around the pin 32 with the pin 116in contact with the tension spring 114, and is restrained from rockingwith its upper left edge 107 pressed against the shoulder portion 66 ofthe release plate 64. As the stopper strip 118 engages the slantingsurface 109 of the operating plate 104 at the cassette insertion asmentioned later, the tension coil spring 114 is previously charged witha necessary force for the cassette ejection and maintained as it is.

The cassette ejecting mechanism 16 includes the ejecting plate 18slidably attached to the baseplate 14 by combinations of the pins 70 and71 and the slots 74 and 75, and the kick plate 76 rockably attached tothe baseplate 14 by the pin 68. As shown in FIGS. 1 and 8, the ejectingplate 18 has a stopper strip 120 bent outward from the right end portionand a pin 122 protruding inward from the middle portion. A tension coilspring 84 is disposed between the stopper strip 120 and the stopperstrip 83 of the baseplate 14 to bias the ejecting plate 18 to the leftof FIG. 1. Thus, the pins 70 and 71 of the baseplate 14 is normallypressed against the right ends of the slots 74 and 75, respectively, ofthe ejecting plate 18. A ring 124 is rockably mounted on the pin 122. Asseen from FIGS. 1 and 9, on the other hand, the kick plate 76 has a pairof inwardly projected pins 126 and 128 and a cam surface 130.

At the cassette ejection, the ejecting plate 18 slides to the right ofFIG. 1, pressed against the biasing force of the tension spring 84. Whenthe ejecting plate 18 slides to the right, the ring 124 of the ejectingplate 18 abuts against the cam surface 130 of the kick plate 76.Thereafter, when the ejecting plate 18 is further pressed, the ring 124rolls along the cam surface 130, and the kick plate 76 is rockedcounterclockwise around the pin 68, accompanying the rightward slide ofthe ejecting plate 18. As the kick plate 76 rocks, the pins 126 and 128are pressed against one end portion 79 of the torsion spring 78 and alower-edge bent strip 132 (see FIG. 2) of the cassette holder 20,respectively. The cassette ejection will be described in detail later.

The tape recorder 10 of the above-mentioned construction is operated asfollows.

Referring to FIG. 1, when the cassette 36 is inserted into the cassetteholder 20, it is first held by the supporting strip 38 of the slider 22.Then, when the cassette 36 is further pushed in, the pins 42 and 43 ofthe slider 22 move to the right, guided by the slots 30 and 31 of thecassette holder 20. Accordingly, the cassette 36 is slid together withthe slider 22 to the right inside the cassette holder 20. When theslider 22 moves to the right, the rocking plate 60, with its ring 88engaged with the guide strip 50, rocks in the clockwise direction aroundthe pin 58 against the biasing force of the toggle spring or tensionspring 62. Further, a shoulder portion 115 of the movable block 40 ofthe slider 22 abuts against the left end 133 of the operating plate 104to press the same, so that the operating plate 104 is moved togetherwith the slider 22 to the right against the biasing force of the tensionspring 114. Thus, in the pushing-in stroke of the cassette insertion,the biasing force of the tension spring 114, as well as that of thetension spring 62, acts as a resisting force on the slider 22. Inparticular, the tension spring 114 is charged with the biasing force inconcert with the slide of the slider 22, and the charged force functionsas the resisting force on the slider 22. In the pushing-in stroke,therefore, the resisting force gradually increases, while the cassetteneed be inserted with a force to overcome such resisting force. Thus, asufficient pushing force is applied to the cassette naturally to ensuresatisfactory insertion of the cassette into the slider 22. Thus, thecassette 36 is inserted while receiving the biasing forces of thetension springs 62 and 114 as resisting forces, and the tension spring114 is charged with biasing force. When the rocking plate 60 passes theneutral point 98 (see FIG. 5), the biasing force of the tension spring62 as the toggle spring functions not as the resisting force but as adrawing-in force to rock the rocking plate 60 in the clockwisedirection. When the slider 22 slides to the right, moreover, the releaseplate 64 is curved outward by the cam strip 46, so that the stopperplate 106 is disengaged from the shoulder portion 66. In the drawing-instroke Ld, the biasing force of the tension spring 114 functions only asa resisting force to prevent the cassette insertion, and is by no meansserviceable. Accordingly, the tension spring 114 is so designed that itsbiasing force may not act on the slider 22 after the slider 22 passesthe neutral point of the toggle spring. The pushing-in stroke Literminating at the neutral point 98 of the toggle spring 62, thehorizontal portions of the slots 102 and 103 of the operating plate 104serve as guide slots for the pins 32 and 33 of the cassette holder 20,and the operating plate 104 moves horizontally. When the rocking plate60 passes the neutral point 98, however, the slanting portions of theslots 102 and 103 guide the pins 32 and 33, respectively, so that theoperating plate 104 descends and moves to the right. As the operatingplate 104 moves down, the left end 133 of the operating plate 104 isdisengaged from the shoulder portion 115 of the movable block 40, andthe extended portion 108 of the operating plate 104 moves to the insideof the stopper plate 106. Then, the slanting surface 109 of theoperating plate 104 is pressed against the stopper strip 118 of thestopper plate 106 by the biasing force of the tension spring 114. Afterthe shoulder portion 115 is disengaged from the left end 133 of theoperating plate 104, the biasing force of the tension spring 114 doesnot act on the slider 22 at all. Namely, the biasing force of thetension spring 114, which acts as a resisting force against the slide ofthe slider 22 in the pushing-in stroke Li, never acts on the slider 22in the drawing-in stroke Ld. The biasing force of the tension spring 114charged in the pushing-in stroke Li is maintained as it is. In thedrawing-in stroke Ld, the biasing force of the tension spring 62 acts asa drawing-in force for the slider 22 and the cassette 36. FIG. 10 showsa state in which the cassette 36 is completely set in the cassetteholder 20 after the end of the drawing-in stroke Ld.

As seen from FIGS. 1 and 10, the one end portion 79 of the torsionspring 78 is not in contact with the pin 126 of the kick plate 76 in thecassette insertion. Therefore, the cassette insertion is not disturbedby the torsion spring 78.

At the end of the drawing-in stroke Ld, the cassette 36 abuts agsinstthe holder supporting plate 80 to rock the same in the clockwisedirection of FIG. 1 around the pin 72 against the biasing force of atorsion spring (not shown). When the holder supporting plate 80 rocks inthe clockwise direction, the cassette holder 20 is released from thesupport by the holder supporting plate 80, and is lowered from an upperposition shown in FIG. 10 to a lower position shown in FIG. 11. Thelower position of FIG. 11 is an operation position, and desired mode,such as the reproduction mode, is set as required by pressing a button,such as e.g. a play button (not shown), by the conventional method tomove the head lever and pinch roller lever.

As mentioned before, the cassette ejection is achieved by pressing theejecting plate 18 in the state of FIG. 11. When the ejecting plate 18 ispressed against the biasing force of the return spring or tension spring84, it is moved horizontally to the right through the engagement of thepins 70 and 71 with the slots 74 and 75. Then, as the ring 124 of theejecting plate 18 abuts against and rolls along the cam surface 130 ofthe kick plate 76, the kick plate 76 rocks in the counterclockwisedirection around the pin 68, as shown in FIG. 12. When the ejectingplate 18 is pressed to rock the kick plate 76, the pins 126 and 128 ofthe kick plate 76 are pressed against the one end portion 79 of thetorsion spring 78 and the lower-edge bent portion 132 of the cassetteholder 20, respectively. As the kick plate 76 rocks, the cassette holder20 moves up, pressed by the pin 128. While the cassette holder 20 isascending, the one end portion 79 of the torsion spring 78 is pressed bythe pin 126 to charge the torsion spring 78 with a biasing force. Thus,the ascent of the cassette holder 20 and the charging of the torsionspring 78 are performed at the same time accompanying the rocking of thekick plate 76, so that the cassette ejection is improved in operatingefficiency, and wrong operation can be avoided. When the cassette holder20 is raised fully, the ring 88 of the rocking plate 60 is caught in theguide slot 48 of the slider 22. The upper portion of the cassette holder20 is regulated by the holder supporting plate 80, which sustains thecassette holder 20 in the upper position. Directly before the cassetteholder 20 reaches the upper position, the shoulder portion 66 of therelease plate 64 engages the upper left edge 107 of the stopper plate106 to prevent the rise of the stopper plate 106. When the cassetteholder 20 is further raised, however, the stopper plate 106 ascends androcks in the counterclockwise direction around the pin 32. As for theoperating plate 104, it moves up together with the cassette holder 20.Accordingly, the rise of the extended portion 108 of the operating plate104 differs from the rise of the stopper strip 118 of the stopper plate106 to cause the slanting surface 109 of the extended portion 108 to bedisengaged from the stopper strip 118. The left end 133 of the operatingplate 104, released from the engagement with the stopper plate 106,presses the shoulder portion 117 of the slider 22 to urge the slider 22to slide to the left by the agency of the biasing force of the tensionspring 114 previously charged at the cassette insertion. The moment thecassette holder 20 reaches the upper position, the slider 22 is slid tothe left by the biasing force of the tension spring 114 charged at thecassette insertion and the biasing force of the torsion spring 78charged by the rocking of the kick plate 76 pressed by the ejectingplate 18, holding the cassette 36. In a stroke corresponding to thedrawing-in stroke Ld for the cassette insertion, the biasing force ofthe toggle spring or tension spring 62 acts on the slider 22 as aresisting force. However, since the biasing force of the tension spring114 charged at the cassette insertion, as well as the biasing force ofthe torsion spring 78 produced at the cassette ejection, acts as anejecting force, so the slider 22 can smoothly slide to the left againstthe resisting force of the tension spring 62. While the slots 30 and 31of the cassette holder 20 each have a length equivalent to the totalstroke (=Li+Ld), the slots 102 and 103 of the operating plate 104 areeach given a length equivalent to the drawing-in stroke Ld for securecontrol of the time when the biasing force of the tension spring 114acts on the slider 22. When the slider 22 slides to the left to reachthe neutral point of the toggle spring 62, the pins 32 and 33 come intocontact with the right ends of the slots 102 and 103, respectively, sothat the biasing force of the tension spring 114 cannot act on theslider 22 any more. After the neutral point of the toggle spring ispassed, however, the leftward slide of the slider 22 is promoted by thebiasing force of the tension spring 62 as the toggle spring newly addedto the biasing force of the torsion spring 78, and thus enough ejectingforce can be obtained. Hereupon, the biasing forces of the ejectingspring 78 and the toggle spring 62 both act on one and the same member,i.e., the rocking plate 60, and are transmitted to the slider 22 throughthe rocking plate 60. Thus, the slider 22 can slide smoothly. Then, thecam surface 136 of the slider 22 comes into contact with the cam surface134 of the operating plate 104 to rock the operating plate 104 in thecounterclockwise direction around the pin 33. At this time, the pin 32is guided by the vertical portion of the slot 32. The stopper plate 106,having its upper left edge 107 engaged with the shoulder portion 66 ofthe release plate 64, urges the operating plate 104 to move upward, withits pin 116 pressing the tension spring 114 sideways. Accordingly, theoperating plate 104 is restored to the position where the left end 133can engage the shoulder portion 115 of the slider 22 after rocking inthe counterclockwise direction (see FIG. 1).

According to the cassette loading/unloading apparatus for cassette taperecorder of this invention, as described above, the slider 22 holds thecassette 36 inserted therein and slides together therewith in thecassette holder 20. Besides the toggle spring (tension spring 78), theapparatus is provided with a separate spring member, e.g., the tensioncoil spring 114, which is charged with a biasing force as the slider 22slides at the cassette insertion so that the charged biasing force mayact as a resisting force on the slider 22. In such an arrangement, thebiasing force of the tension spring 114, as well as that of the togglespring, will be able to act as the resulting force on the slider 22 evenif the pushing-in stroke is small. Accordingly, the cassette is insertedinto the cassette holder with a sufficient pushing force at the cassetteinsertion, so that secure cassette loading may be ensured. Preferably,the spring member is so designed that the resisting force against theslider may be checked by the stopper plate after the slider passes theneutral point of the toggle spring. Thus, the drawing-in stroke maysmoothly be covered by allowing the biasing force to be applied to theslider only in the pushing-in stroke, that is, by preventing the biasingforce from being applied to the slider in the drawing-in stroke.

The biasing force of the spring member charged in the pushing-in strokemay be either maintained as it is or dischaged. Preferably, however, thespring member is kept charged with the biasing force so that the chargedbiasing force may be utilized as an ejecting force in the ejectingstroke.

What is claimed is:
 1. A cassette loading/unloading apparatus for aslot-in type cassette tape recorder using a toggle spring, characterizedin that a slider holds a cassette inserted therein and slides togethertherewith in a cassette holder, and that a spring member to be chargedwith a biasing force as the slider slides at cassette insertion isprovided separately from the toggle spring so that the charged biasingforce may act as a resisting force on the slider, said spring memberapplying the resisting force to the slider before the slider passes theneutral point of the toggle spring, and being prevented from applyingthe resisting force to the slider after the slider passes the neutralpoint.
 2. A cassette loading/unloading apparatus according to claim 1,wherein an operating plate is slidably mounted on the cassette holder,said operating plate sliding together with the slider before the sliderpasses the neutral point of the toggle spring, and being disengaged fromthe slider after the slider passes the neutral point, and said springmember is disposed between the operating plate and a baseplate and ischarged with the biasing force as the operating plate slides in concertwith the slider.
 3. A cassette loading/unloading apparatus according toclaim 2, wherein said slider has a first shoulder portion to engage theoperating plate to slide together therewith at the cassette insertion,and said operating plate has a pair of slots to be guided by a pair ofguide pins attached to the cassette holder, each said slot including ahorizontal portion to allow horizontal slide of the operating plate anda slanting portion to cause the operating plate to be disengaged fromthe first shoulder portion of the slider when the slider passes theneutral point at the cassette insertion.
 4. A cassette loading/unloadingapparatus according to claim 3, wherein a stopper plate is rockablyattached to the cassette holder, said stopper plate rocking to stop theoperating plate when the slider passes the neutral point at the cassetteinsertion so that the operating plate disengaged from the slider may bekept charged with the biasing force of said spring member.
 5. A cassetteloading/unloading apparatus according to claim 4, wherein said pair ofslots of the stopper plate each have a horizontal length equivalent tothe drawing-in stroke of the cassette insertion, said stopper plate hasa pin to engage the return spring for the operating plate to urge thestopper plate to rock and a stopper strip capable of engaging theoperating plate, a release plate formed of a leaf spring is attached tothe baseplate, said release plate having a shoulder portion to beengaged with the stopper plate to maintain the stopper plate in theposition before rocking, a cam strip is attached to the slider, wherebythe release plate is deformed so that the stopper plate is disengagedfrom the shoulder portion of the release plate to allow the stopperplate to rock when the slider passes the neutral point at the cassetteinsertion, and said slider further has a second shoulder portion locatedbelow the first shoulder portion to be engaged with the operating platein the cassette ejecting stroke corresponding to the pushing-in stroke.